iNEMI Releases Lead-Free Process Book

Everything you need to know about lead-free solder manufacturing processes in one volume? Not quite, but this book gathers a wide range of real-world and test info.

The International Electronic Manufacturing Initiative (iNEMI) has released the book, Lead-Free Solder Process Development, published by Wiley-IEEE Press. Several iNEMI project leaders and participants were involved in writing the book, which is designed to be a reference guide for engineers in the electronics manufacturing industry who are -- or will be -- migrating to lead-free soldering.

The 250-page book covers lead-free topics that include legislation, SMT, wave soldering, rework, BGA/CSP component alloys, tin whiskers, testability, mechanical reliability, aerospace/military reliability, and automotive reliability. Each subject is discussed by experts who have conducted work in the field and can provide insights into the most important considerations. The book also points to updates on ongoing research-and-development that's being conducted by iNEMI industry groups.

The book covers a wide range of issues directly related to the work of design engineers, according to Jasbir Bath, a consultant and one of the book's co-editors. “The book looks at the regulations, including EU RoHS, China RoHS, and Korea RoHS,” Bath tells us. “It walks the engineer through the issues of moving to lead-free soldering. That includes component soldering defects such as head in pillow [incomplete wetting], as well as other components defects. The book also discusses warpage on the board. Design engineers need to be fully aware of these manufacturing issues.”

Bath notes the text looks at the changes in wave soldering when you move from lead to lead-free. “We also cover design guidelines. What pin-to-hole area ratios? With lead-free, the ratio is tighter.”

The text also explores rework, looking at the challenges. “What does the design engineer need to be aware of with rework?” says Bath. “With lead-free there will be more defects. There is more likelihood you will dissolve more of the copper, so you will need thicker copper plates, more plating.”

Another challenge for design engineers is the need to make sure there are mitigation strategies to avoid tin whisker growth. “One chapter looks at the type of components that develop whisker growth. Design engineers need to know this as they spec components.” Bath notes there are also chapters that cover the unique challenges in the automotive and aerospace industries. These include the soldering defects and possible tin whisker growth that can occur in the specific environment of aerospace and automotive manufacturing, as well as the stress factors these products go through during their lifecycles.

The book’s editors include a number of experts on lead-free technology, including Gregory Henshall (HP), chairman of iNEMI’s Characterization of Pb-Free Alloys project; Jasbir Bath (iNEMI), co-chairman of the Pb-Free Rework Optimization Project; and Carol Handwerker (Purdue University), co-chairman of iNEMI’s Research Committee. In addition, half of the book’s 10 chapters were written by iNEMI members from Cisco, Delphi, Flextronics, HP, and Intel.

While much of the information has been available in various Websites and academic publications for some time, the convenience of a one-stop volume makes the book handy. The new material in the book -- perhaps the real nugget of value -- comes from the updates provided by iNEMI's industry working groups.

Lead-Free Solder Process Development is available from the Wiley-IEEE Website, as well as through Amazon.

While the switch to lead-free solder has been completed across much of the electronics industry (some areas are exempt), the directives related to hazardous materials are an ongoing work in progress. The European Union has just published a revised version of RoHS. Look for an item on that in the next fews days. India has just announced its own RoHS regulations.

The good news is that after three or four years of using lead-free solder, there have not been major reliability problems. Look for an article on that subject in the next week.

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